The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
A typical freight train is composed of one or more locomotives and a plurality of railcars with which to haul freight. A locomotive is supported by two or more truck assemblies (hereinafter referred to as "trucks"). FIG. 1 illustrates a locomotive 1 that employs only two trucks, one truck 2 supporting the front of the locomotive and the other truck 3 supporting its rear. Although the trucks shown in FIG. 1 each have only two wheel/axle assemblies 4 (commonly referred to as "wheelsets"), there are locomotives in use in the railroad industry whose trucks employ three or even four wheelsets.
In addition to its wheelsets, each truck features a suspension system, a pair of side frames and the other parts that together form the structure that supports the body of the locomotive. The wheelsets 4 of each truck are disposed in parallel. Each wheelset 4 is composed of an axle shaft 5 and two wheels 6. Each axle shaft 5 has a bearing assembly 7 concentrically fixed about each of its ends. Each wheel 6 is fixed to its axle shaft 5 inboard of, and adjacent to, its neighboring bearing assembly 7. FIG. 1 only shows the near side of the axle shafts 5, wheels 6 and bearing assemblies 7 of the two trucks 2 and 3. The far side (not shown) of each truck is, of course, essentially a mirror image of the near side.
FIG. 1 also shows that the wheelsets 4 of each truck on the near side are interconnected. by a side frame 8. Likewise, another side frame (not shown) interconnects the wheelsets 4 of each truck on the far side. In particular, each side frame has an opening at each end. These openings are each shaped to accommodate the correspondingly shaped external housing of a bearing assembly 7. By its openings, one side frame 8 affixes to, and rides upon, the two bearing housings 7 on the near side of the wheelsets 4 of truck 2. Another side frame 8 affixes to, and rides upon, the two bearing housings 7 for the wheelsets 4 on the near side of truck 3. Likewise, each truck also has a side frame on the far side that affixes to the two bearing housings located on that side of the wheelsets 4.
The weight of the body of the locomotive 1 is transferred to the side frames 8, and other supporting components, via the suspension systems (not shown) on the trucks. It is the function of the suspension systems to dampen the vibrations that occur between the wheelsets 4 and the body of the locomotive 1. The side frames 8 of the trucks transfer the weight of the locomotive body to the wheelsets 4 of the locomotive 1 via the bearing housings 7. Being fixed within the openings and thus rendered immovable by the side frames, the bearing housings, via the bearings they carry, allow the axle shafts 5 to rotate as the wheels 6 ride atop the rails of the railway track.
FIG. 2 shows a wheelset 4 of a locomotive truck to which a traction motor 9 is attached. This type of wheelset 4 has a gear wheel 10 fixed about its axle shaft 5 inboard of the wheel 6 shown at right. The pinion gear 11 on the shaft 12 of the traction motor 9 is designed to mesh with the gear wheel 10 of its corresponding wheelset 4. Controlled by a train operator situated in the cab of the locomotive 1, the locomotive engines supply the desired amount of electrical power to the traction motors 9 on the trucks. In this way, each traction motor 9 drives the gear wheel 10 of its corresponding wheelset 4 to rotate the wheels 6 and thus propel the locomotive 1 and its railcars along the railway track.
The interaction between the wheels and the tracks on which they ride depends on many factors such as the type of railcar or locomotive to which the wheels are mounted, the environment in which the wheels are used, the weight they bear, and the specific composition and physical profile of the individual wheels. These factors are discussed in depth in THE CAR AND LOCOMOTIVE CYCLOPEDIA OF AMERICAN PRACTICES, 6.sup.th edition, .RTM. 1997, published by Simmons-Boardman Books, Inc., incorporated herein by reference.
An example of the physical profile for one type of wheel is illustrated in FIG. 2. Bounded longitudinally by back and front faces 61 and 62, the hub 60 defines a hole (commonly referred to as the "wheel bore") in the center of wheel 6. It is by the wheel bore that the wheel 6 is tightly press-fitted on, and mounted radially about, the wheel seat 51 on axle shaft 5. Emerging from the back and front fillets 63 and 64 of hub 60, the plate 65 extends radially outward from the hub 60. Formed on the outermost periphery of plate 65 is rim 66. Bounded longitudinally by back and front faces 67 and 68, the rim 66 emerges from the plate 65 via its back and front fillets 69 and 70. On the outer circumference of the rim 66 is the area known as the tread 71. Depending on the type of wheel, the contour of the tread 71 may be flat or tapered. The flange 72 of the wheel 6 is formed on the periphery of rim 66, emerging from the back rim face 67. The curved portion of the rim 66 formed at the site where the tread 71 and flange 72 meet is referred to as the flange throat 73.
The wheel treads 71 are designed to adhere to the running (i.e., top) surface of the rails essentially by means of friction. It is this friction between the treads 71 and the running surface of the rails that allows the wheels 6 to gain traction on the rails as the traction motors 9 rotate the wheelsets 4 and thereby propel the train along the railway tracks. As alluded to above, a wheel flange 72 is the tapered projection that extends completely around the inner portion of the rim 66 of a wheel 6. Together, the wheel flanges 72 of each wheelset 4 are designed to keep the wheelset on the railway track by limiting lateral movement of the wheelset 4 against the inside surfaces of either rail.
Due to their contact with the railway track, the wheels 6 of a locomotive suffer wear over time, particularly on their treads 71 and, to a lesser extent, their flanges 72. The treads 71, of course, wear as a result of their direct contact against the running surface of the steel rails. During braking, the treads 71 may suffer wear more severely if the wheels should slip or lockup as they slide atop the rails. The wheel flanges 72 suffer wear due to their contact with inside surfaces of the rails, particularly as the trains negotiate curves in the railway track.
The most important goal of the railroad industry has always been to assure the safety of the passengers and freight that it transports by rail. The integrity of every wheel on a train is therefore of critical importance. A defective or badly worn wheel is likely to lead to a derailment of the train, resulting in serious injuries to passengers or damage to freight. The industry has continually sought to improve the durability and reliability of the wheels, a fact that can be quickly appreciated at a glance by observing a long freight train operating at high speed. Every year the railroad operating authorities spend large amounts of money to inspect, replace, and maintain the wheels on their trains. The industry has long employed procedures to detect worn or defective wheels and promptly remove them from service. The industry also continually makes efforts to improve the processes that manufactures use to make wheels and the systems that the railroads employ to maintain them while in service.
Wheel flange lubrication systems are illustrative of the many systems that the railroad industry uses to prolong the useful life of the wheels. FIG. 3 depicts one type of lubrication system that is used to lubricate the flanges of the wheels of a railroad locomotive. The lubrication system 20 features a refillable reservoir 21, a pump 22, an air control unit 23, spray nozzles 24, and an electronic controller 25 to control the overall operation of the system. The reservoir 21 holds the lubricant, 42 or 58 gallon capacities are often required. The air control unit 23 connects via an inlet line 26 to a source of pressurized air, typically the main reservoir on the locomotive. It houses two solenoids (not shown), the pump solenoid for the lubricant pump 22 and the spray solenoid for the nozzles 24. It also contains a regulator to regulate the pressure of the air supplied to the pump 22. The pressure supplied to the pump 22, from the main reservoir of the locomotive, is typically regulated to 76 psi. The pump 22 is mounted to the bottom of the lubricant reservoir 21 from which it is gravity fed lubricant through a filter (not shown). Powered by a dc source via wires 27, the electronic controller 25 directly controls the solenoids and, through the solenoids, indirectly controls the pump and nozzles. The pump 22 is pneumatically activated by the pump solenoid, allowing the pump to supply lubricant at a preset pressure (e.g., 400 psi) to the spray nozzles 24 via conduits 28. The spray nozzles 24 are also connected to the spray solenoid via lines 29 from which they receive a pulse of pressurized air when the spray solenoid is energized by the electronic controller 25. Mounted to a suitable spot on its truck, each spray nozzle 24 is aimed directly at one of the wheel flanges on the locomotive.
The electronic controller 25 receives input from the axle generator on the locomotive, via wires 30. Optionally, the electronic controller 25 may also receive other inputs, such as signals indicative of when the locomotive is traveling on curved railway track and to which direction the track is presently curving. The electronic controller 25 may also receive inputs 31 indicative of when it should inhibit the lubrication system from operating, such as when the wheels are slipping or during sanding (i.e., when sand is being applied to the rails in front of the wheels 6 of the wheelsets 4 to improve traction).
Operating according to its programming, the electronic controller 25 monitors the signal from the generator to keep track of the speed of the locomotive and the distance that it has traveled. Primed by the pump 22 via conduits 28 with pressurized lubricant from the reservoir 21, each nozzle always stands ready to spray lubricant onto its corresponding wheel flange. The electronic controller 25 can be set to energize the spray solenoid at predetermined intervals, such as at every 10 to 590 feet that the locomotive travels. When energized, the spray solenoid allows pressurized air to pass from the inlet line 26 through the spray solenoid and lines 29 to the nozzles 24. Each time the controller 25 energizes the spray solenoid a pulse of pressurized air flows to the nozzles 24. Ideally, all of the nozzles respond to this pulse in the same manner. Not only does the pulse open each nozzle 24 but, in doing so, shoots with it a dose of lubricant that each nozzle sprays onto the wheel flange of the locomotive at which it is aimed. The electronic controller 25 thus operates the nozzles 24 according to a duty cycle, i.e., dispensing lubricant during a squirt phase and being closed otherwise during an inactive phase of the duty cycle. Moreover, at a desired rate (e.g., every twelve nozzle squirts), the controller 25 energizes the pump solenoid so that the pressure of the lubricant at the nozzles 24 is maintained at the preset level.
The nozzles 24 have proven to be the least reliable components of the wheel flange lubrication system. These prior art nozzles 24 have traditionally employed internally a steel ball as a check valve to prevent or permit the delivery of the dose of lubricant. While the spray solenoid is deenergized, the ball valve within the nozzle is biased to a closed position in which the pressurized lubricant is blocked from exiting the nozzle. When the spray solenoid is energized, however, the force of the incoming pulse of air moves the ball valve to an open position and allows the incoming pulse of air to shoot the dose of lubricant out of the nozzle and onto the wheel flange.
The prior art nozzle, however, has not faired well in the environment in which it was intended to be used. It has exhibited at least three modes of failure. Railroad personnel have reported that the nozzles often function intermittently. A typical complaint would be that a nozzle would work fine for a while, then stop working, work again, and quit yet again. It was also observed that the nozzles would often drool. Instead of shutting-off when the spray solenoid was deenergized, the nozzles would continue to allow lubricant to seep out during the inactive phase. Locomotives on which this drooling problem occurred would often waste rather copious amounts of lubricant. Swings in temperature also adversely affected the operation of the nozzles. The dose of lubricant squirted by a nozzle would increase as the temperature rose. Conversely, as the temperature decreased, the dose of lubricant squirted by a nozzle would decrease.
The design of the nozzle not only left it quite vulnerable to contamination but also was responsible for its sensitivity to temperature. Dirt, dust and other debris would work its way inside the nozzle and soon impede the motion of its internal ball valve. The ball valve would begin to stick, sporadically at first, and eventually close permanently or fail to close fully, regardless of the state of the spray solenoid. This vulnerability to contamination explained the intermittency and drooling problems, and thermal susceptibility explained the variation in the amount of lubricant the nozzle dispensed.